1 =====================
2 The Linux IPMI Driver
3 =====================
4
5 :Author: Corey Minyard <minyard@mvista.com> / <minyard@acm.org>
6
7 The Intelligent Platform Management Interface, or IPMI, is a
8 standard for controlling intelligent devices that monitor a system.
9 It provides for dynamic discovery of sensors in the system and the
10 ability to monitor the sensors and be informed when the sensor's
11 values change or go outside certain boundaries. It also has a
12 standardized database for field-replaceable units (FRUs) and a watchdog
13 timer.
14
15 To use this, you need an interface to an IPMI controller in your
16 system (called a Baseboard Management Controller, or BMC) and
17 management software that can use the IPMI system.
18
19 This document describes how to use the IPMI driver for Linux. If you
20 are not familiar with IPMI itself, see the web site at
21 https://www.intel.com/design/servers/ipmi/index.htm. IPMI is a big
22 subject and I can't cover it all here!
23
24 Configuration
25 -------------
26
27 The Linux IPMI driver is modular, which means you have to pick several
28 things to have it work right depending on your hardware. Most of
29 these are available in the 'Character Devices' menu then the IPMI
30 menu.
31
32 No matter what, you must pick 'IPMI top-level message handler' to use
33 IPMI. What you do beyond that depends on your needs and hardware.
34
35 The message handler does not provide any user-level interfaces.
36 Kernel code (like the watchdog) can still use it. If you need access
37 from userland, you need to select 'Device interface for IPMI' if you
38 want access through a device driver.
39
40 The driver interface depends on your hardware. If your system
41 properly provides the SMBIOS info for IPMI, the driver will detect it
42 and just work. If you have a board with a standard interface (These
43 will generally be either "KCS", "SMIC", or "BT", consult your hardware
44 manual), choose the 'IPMI SI handler' option. A driver also exists
45 for direct I2C access to the IPMI management controller. Some boards
46 support this, but it is unknown if it will work on every board. For
47 this, choose 'IPMI SMBus handler', but be ready to try to do some
48 figuring to see if it will work on your system if the SMBIOS/APCI
49 information is wrong or not present. It is fairly safe to have both
50 these enabled and let the drivers auto-detect what is present.
51
52 You should generally enable ACPI on your system, as systems with IPMI
53 can have ACPI tables describing them.
54
55 If you have a standard interface and the board manufacturer has done
56 their job correctly, the IPMI controller should be automatically
57 detected (via ACPI or SMBIOS tables) and should just work. Sadly,
58 many boards do not have this information. The driver attempts
59 standard defaults, but they may not work. If you fall into this
60 situation, you need to read the section below named 'The SI Driver' or
61 "The SMBus Driver" on how to hand-configure your system.
62
63 IPMI defines a standard watchdog timer. You can enable this with the
64 'IPMI Watchdog Timer' config option. If you compile the driver into
65 the kernel, then via a kernel command-line option you can have the
66 watchdog timer start as soon as it initializes. It also have a lot
67 of other options, see the 'Watchdog' section below for more details.
68 Note that you can also have the watchdog continue to run if it is
69 closed (by default it is disabled on close). Go into the 'Watchdog
70 Cards' menu, enable 'Watchdog Timer Support', and enable the option
71 'Disable watchdog shutdown on close'.
72
73 IPMI systems can often be powered off using IPMI commands. Select
74 'IPMI Poweroff' to do this. The driver will auto-detect if the system
75 can be powered off by IPMI. It is safe to enable this even if your
76 system doesn't support this option. This works on ATCA systems, the
77 Radisys CPI1 card, and any IPMI system that supports standard chassis
78 management commands.
79
80 If you want the driver to put an event into the event log on a panic,
81 enable the 'Generate a panic event to all BMCs on a panic' option. If
82 you want the whole panic string put into the event log using OEM
83 events, enable the 'Generate OEM events containing the panic string'
84 option. You can also enable these dynamically by setting the module
85 parameter named "panic_op" in the ipmi_msghandler module to "event"
86 or "string". Setting that parameter to "none" disables this function.
87
88 Basic Design
89 ------------
90
91 The Linux IPMI driver is designed to be very modular and flexible, you
92 only need to take the pieces you need and you can use it in many
93 different ways. Because of that, it's broken into many chunks of
94 code. These chunks (by module name) are:
95
96 ipmi_msghandler - This is the central piece of software for the IPMI
97 system. It handles all messages, message timing, and responses. The
98 IPMI users tie into this, and the IPMI physical interfaces (called
99 System Management Interfaces, or SMIs) also tie in here. This
100 provides the kernelland interface for IPMI, but does not provide an
101 interface for use by application processes.
102
103 ipmi_devintf - This provides a userland IOCTL interface for the IPMI
104 driver, each open file for this device ties in to the message handler
105 as an IPMI user.
106
107 ipmi_si - A driver for various system interfaces. This supports KCS,
108 SMIC, and BT interfaces. Unless you have an SMBus interface or your
109 own custom interface, you probably need to use this.
110
111 ipmi_ssif - A driver for accessing BMCs on the SMBus. It uses the
112 I2C kernel driver's SMBus interfaces to send and receive IPMI messages
113 over the SMBus.
114
115 ipmi_powernv - A driver for access BMCs on POWERNV systems.
116
117 ipmi_watchdog - IPMI requires systems to have a very capable watchdog
118 timer. This driver implements the standard Linux watchdog timer
119 interface on top of the IPMI message handler.
120
121 ipmi_poweroff - Some systems support the ability to be turned off via
122 IPMI commands.
123
124 bt-bmc - This is not part of the main driver, but instead a driver for
125 accessing a BMC-side interface of a BT interface. It is used on BMCs
126 running Linux to provide an interface to the host.
127
128 These are all individually selectable via configuration options.
129
130 Much documentation for the interface is in the include files. The
131 IPMI include files are:
132
133 linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI.
134
135 linux/ipmi_smi.h - Contains the interface for system management interfaces
136 (things that interface to IPMI controllers) to use.
137
138 linux/ipmi_msgdefs.h - General definitions for base IPMI messaging.
139
140
141 Addressing
142 ----------
143
144 The IPMI addressing works much like IP addresses, you have an overlay
145 to handle the different address types. The overlay is::
146
147 struct ipmi_addr
148 {
149 int addr_type;
150 short channel;
151 char data[IPMI_MAX_ADDR_SIZE];
152 };
153
154 The addr_type determines what the address really is. The driver
155 currently understands two different types of addresses.
156
157 "System Interface" addresses are defined as::
158
159 struct ipmi_system_interface_addr
160 {
161 int addr_type;
162 short channel;
163 };
164
165 and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking
166 straight to the BMC on the current card. The channel must be
167 IPMI_BMC_CHANNEL.
168
169 Messages that are destined to go out on the IPMB bus going through the
170 BMC use the IPMI_IPMB_ADDR_TYPE address type. The format is::
171
172 struct ipmi_ipmb_addr
173 {
174 int addr_type;
175 short channel;
176 unsigned char slave_addr;
177 unsigned char lun;
178 };
179
180 The "channel" here is generally zero, but some devices support more
181 than one channel, it corresponds to the channel as defined in the IPMI
182 spec.
183
184 There is also an IPMB direct address for a situation where the sender
185 is directly on an IPMB bus and doesn't have to go through the BMC.
186 You can send messages to a specific management controller (MC) on the
187 IPMB using the IPMI_IPMB_DIRECT_ADDR_TYPE with the following format::
188
189 struct ipmi_ipmb_direct_addr
190 {
191 int addr_type;
192 short channel;
193 unsigned char slave_addr;
194 unsigned char rq_lun;
195 unsigned char rs_lun;
196 };
197
198 The channel is always zero. You can also receive commands from other
199 MCs that you have registered to handle and respond to them, so you can
200 use this to implement a management controller on a bus..
201
202 Messages
203 --------
204
205 Messages are defined as::
206
207 struct ipmi_msg
208 {
209 unsigned char netfn;
210 unsigned char lun;
211 unsigned char cmd;
212 unsigned char *data;
213 int data_len;
214 };
215
216 The driver takes care of adding/stripping the header information. The
217 data portion is just the data to be send (do NOT put addressing info
218 here) or the response. Note that the completion code of a response is
219 the first item in "data", it is not stripped out because that is how
220 all the messages are defined in the spec (and thus makes counting the
221 offsets a little easier :-).
222
223 When using the IOCTL interface from userland, you must provide a block
224 of data for "data", fill it, and set data_len to the length of the
225 block of data, even when receiving messages. Otherwise the driver
226 will have no place to put the message.
227
228 Messages coming up from the message handler in kernelland will come in
229 as::
230
231 struct ipmi_recv_msg
232 {
233 struct list_head link;
234
235 /* The type of message as defined in the "Receive Types"
236 defines above. */
237 int recv_type;
238
239 ipmi_user_t *user;
240 struct ipmi_addr addr;
241 long msgid;
242 struct ipmi_msg msg;
243
244 /* Call this when done with the message. It will presumably free
245 the message and do any other necessary cleanup. */
246 void (*done)(struct ipmi_recv_msg *msg);
247
248 /* Place-holder for the data, don't make any assumptions about
249 the size or existence of this, since it may change. */
250 unsigned char msg_data[IPMI_MAX_MSG_LENGTH];
251 };
252
253 You should look at the receive type and handle the message
254 appropriately.
255
256
257 The Upper Layer Interface (Message Handler)
258 -------------------------------------------
259
260 The upper layer of the interface provides the users with a consistent
261 view of the IPMI interfaces. It allows multiple SMI interfaces to be
262 addressed (because some boards actually have multiple BMCs on them)
263 and the user should not have to care what type of SMI is below them.
264
265
266 Watching For Interfaces
267 ^^^^^^^^^^^^^^^^^^^^^^^
268
269 When your code comes up, the IPMI driver may or may not have detected
270 if IPMI devices exist. So you might have to defer your setup until
271 the device is detected, or you might be able to do it immediately.
272 To handle this, and to allow for discovery, you register an SMI
273 watcher with ipmi_smi_watcher_register() to iterate over interfaces
274 and tell you when they come and go.
275
276
277 Creating the User
278 ^^^^^^^^^^^^^^^^^
279
280 To use the message handler, you must first create a user using
281 ipmi_create_user. The interface number specifies which SMI you want
282 to connect to, and you must supply callback functions to be called
283 when data comes in. The callback function can run at interrupt level,
284 so be careful using the callbacks. This also allows to you pass in a
285 piece of data, the handler_data, that will be passed back to you on
286 all calls.
287
288 Once you are done, call ipmi_destroy_user() to get rid of the user.
289
290 From userland, opening the device automatically creates a user, and
291 closing the device automatically destroys the user.
292
293
294 Messaging
295 ^^^^^^^^^
296
297 To send a message from kernel-land, the ipmi_request_settime() call does
298 pretty much all message handling. Most of the parameter are
299 self-explanatory. However, it takes a "msgid" parameter. This is NOT
300 the sequence number of messages. It is simply a long value that is
301 passed back when the response for the message is returned. You may
302 use it for anything you like.
303
304 Responses come back in the function pointed to by the ipmi_recv_hndl
305 field of the "handler" that you passed in to ipmi_create_user().
306 Remember again, these may be running at interrupt level. Remember to
307 look at the receive type, too.
308
309 From userland, you fill out an ipmi_req_t structure and use the
310 IPMICTL_SEND_COMMAND ioctl. For incoming stuff, you can use select()
311 or poll() to wait for messages to come in. However, you cannot use
312 read() to get them, you must call the IPMICTL_RECEIVE_MSG with the
313 ipmi_recv_t structure to actually get the message. Remember that you
314 must supply a pointer to a block of data in the msg.data field, and
315 you must fill in the msg.data_len field with the size of the data.
316 This gives the receiver a place to actually put the message.
317
318 If the message cannot fit into the data you provide, you will get an
319 EMSGSIZE error and the driver will leave the data in the receive
320 queue. If you want to get it and have it truncate the message, us
321 the IPMICTL_RECEIVE_MSG_TRUNC ioctl.
322
323 When you send a command (which is defined by the lowest-order bit of
324 the netfn per the IPMI spec) on the IPMB bus, the driver will
325 automatically assign the sequence number to the command and save the
326 command. If the response is not receive in the IPMI-specified 5
327 seconds, it will generate a response automatically saying the command
328 timed out. If an unsolicited response comes in (if it was after 5
329 seconds, for instance), that response will be ignored.
330
331 In kernelland, after you receive a message and are done with it, you
332 MUST call ipmi_free_recv_msg() on it, or you will leak messages. Note
333 that you should NEVER mess with the "done" field of a message, that is
334 required to properly clean up the message.
335
336 Note that when sending, there is an ipmi_request_supply_msgs() call
337 that lets you supply the smi and receive message. This is useful for
338 pieces of code that need to work even if the system is out of buffers
339 (the watchdog timer uses this, for instance). You supply your own
340 buffer and own free routines. This is not recommended for normal use,
341 though, since it is tricky to manage your own buffers.
342
343
344 Events and Incoming Commands
345 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
346
347 The driver takes care of polling for IPMI events and receiving
348 commands (commands are messages that are not responses, they are
349 commands that other things on the IPMB bus have sent you). To receive
350 these, you must register for them, they will not automatically be sent
351 to you.
352
353 To receive events, you must call ipmi_set_gets_events() and set the
354 "val" to non-zero. Any events that have been received by the driver
355 since startup will immediately be delivered to the first user that
356 registers for events. After that, if multiple users are registered
357 for events, they will all receive all events that come in.
358
359 For receiving commands, you have to individually register commands you
360 want to receive. Call ipmi_register_for_cmd() and supply the netfn
361 and command name for each command you want to receive. You also
362 specify a bitmask of the channels you want to receive the command from
363 (or use IPMI_CHAN_ALL for all channels if you don't care). Only one
364 user may be registered for each netfn/cmd/channel, but different users
365 may register for different commands, or the same command if the
366 channel bitmasks do not overlap.
367
368 To respond to a received command, set the response bit in the returned
369 netfn, use the address from the received message, and use the same
370 msgid that you got in the receive message.
371
372 From userland, equivalent IOCTLs are provided to do these functions.
373
374
375 The Lower Layer (SMI) Interface
376 -------------------------------
377
378 As mentioned before, multiple SMI interfaces may be registered to the
379 message handler, each of these is assigned an interface number when
380 they register with the message handler. They are generally assigned
381 in the order they register, although if an SMI unregisters and then
382 another one registers, all bets are off.
383
384 The ipmi_smi.h defines the interface for management interfaces, see
385 that for more details.
386
387
388 The SI Driver
389 -------------
390
391 The SI driver allows KCS, BT, and SMIC interfaces to be configured
392 in the system. It discovers interfaces through a host of different
393 methods, depending on the system.
394
395 You can specify up to four interfaces on the module load line and
396 control some module parameters::
397
398 modprobe ipmi_si.o type=<type1>,<type2>....
399 ports=<port1>,<port2>... addrs=<addr1>,<addr2>...
400 irqs=<irq1>,<irq2>...
401 regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,...
402 regshifts=<shift1>,<shift2>,...
403 slave_addrs=<addr1>,<addr2>,...
404 force_kipmid=<enable1>,<enable2>,...
405 kipmid_max_busy_us=<ustime1>,<ustime2>,...
406 unload_when_empty=[0|1]
407 trydmi=[0|1] tryacpi=[0|1]
408 tryplatform=[0|1] trypci=[0|1]
409
410 Each of these except try... items is a list, the first item for the
411 first interface, second item for the second interface, etc.
412
413 The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it
414 defaults to "kcs".
415
416 If you specify addrs as non-zero for an interface, the driver will
417 use the memory address given as the address of the device. This
418 overrides si_ports.
419
420 If you specify ports as non-zero for an interface, the driver will
421 use the I/O port given as the device address.
422
423 If you specify irqs as non-zero for an interface, the driver will
424 attempt to use the given interrupt for the device.
425
426 The other try... items disable discovery by their corresponding
427 names. These are all enabled by default, set them to zero to disable
428 them. The tryplatform disables openfirmware.
429
430 The next three parameters have to do with register layout. The
431 registers used by the interfaces may not appear at successive
432 locations and they may not be in 8-bit registers. These parameters
433 allow the layout of the data in the registers to be more precisely
434 specified.
435
436 The regspacings parameter give the number of bytes between successive
437 register start addresses. For instance, if the regspacing is set to 4
438 and the start address is 0xca2, then the address for the second
439 register would be 0xca6. This defaults to 1.
440
441 The regsizes parameter gives the size of a register, in bytes. The
442 data used by IPMI is 8-bits wide, but it may be inside a larger
443 register. This parameter allows the read and write type to specified.
444 It may be 1, 2, 4, or 8. The default is 1.
445
446 Since the register size may be larger than 32 bits, the IPMI data may not
447 be in the lower 8 bits. The regshifts parameter give the amount to shift
448 the data to get to the actual IPMI data.
449
450 The slave_addrs specifies the IPMI address of the local BMC. This is
451 usually 0x20 and the driver defaults to that, but in case it's not, it
452 can be specified when the driver starts up.
453
454 The force_ipmid parameter forcefully enables (if set to 1) or disables
455 (if set to 0) the kernel IPMI daemon. Normally this is auto-detected
456 by the driver, but systems with broken interrupts might need an enable,
457 or users that don't want the daemon (don't need the performance, don't
458 want the CPU hit) can disable it.
459
460 If unload_when_empty is set to 1, the driver will be unloaded if it
461 doesn't find any interfaces or all the interfaces fail to work. The
462 default is one. Setting to 0 is useful with the hotmod, but is
463 obviously only useful for modules.
464
465 When compiled into the kernel, the parameters can be specified on the
466 kernel command line as::
467
468 ipmi_si.type=<type1>,<type2>...
469 ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>...
470 ipmi_si.irqs=<irq1>,<irq2>...
471 ipmi_si.regspacings=<sp1>,<sp2>,...
472 ipmi_si.regsizes=<size1>,<size2>,...
473 ipmi_si.regshifts=<shift1>,<shift2>,...
474 ipmi_si.slave_addrs=<addr1>,<addr2>,...
475 ipmi_si.force_kipmid=<enable1>,<enable2>,...
476 ipmi_si.kipmid_max_busy_us=<ustime1>,<ustime2>,...
477
478 It works the same as the module parameters of the same names.
479
480 If your IPMI interface does not support interrupts and is a KCS or
481 SMIC interface, the IPMI driver will start a kernel thread for the
482 interface to help speed things up. This is a low-priority kernel
483 thread that constantly polls the IPMI driver while an IPMI operation
484 is in progress. The force_kipmid module parameter will all the user to
485 force this thread on or off. If you force it off and don't have
486 interrupts, the driver will run VERY slowly. Don't blame me,
487 these interfaces suck.
488
489 Unfortunately, this thread can use a lot of CPU depending on the
490 interface's performance. This can waste a lot of CPU and cause
491 various issues with detecting idle CPU and using extra power. To
492 avoid this, the kipmid_max_busy_us sets the maximum amount of time, in
493 microseconds, that kipmid will spin before sleeping for a tick. This
494 value sets a balance between performance and CPU waste and needs to be
495 tuned to your needs. Maybe, someday, auto-tuning will be added, but
496 that's not a simple thing and even the auto-tuning would need to be
497 tuned to the user's desired performance.
498
499 The driver supports a hot add and remove of interfaces. This way,
500 interfaces can be added or removed after the kernel is up and running.
501 This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a
502 write-only parameter. You write a string to this interface. The string
503 has the format::
504
505 <op1>[:op2[:op3...]]
506
507 The "op"s are::
508
509 add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]]
510
511 You can specify more than one interface on the line. The "opt"s are::
512
513 rsp=<regspacing>
514 rsi=<regsize>
515 rsh=<regshift>
516 irq=<irq>
517 ipmb=<ipmb slave addr>
518
519 and these have the same meanings as discussed above. Note that you
520 can also use this on the kernel command line for a more compact format
521 for specifying an interface. Note that when removing an interface,
522 only the first three parameters (si type, address type, and address)
523 are used for the comparison. Any options are ignored for removing.
524
525 The SMBus Driver (SSIF)
526 -----------------------
527
528 The SMBus driver allows up to 4 SMBus devices to be configured in the
529 system. By default, the driver will only register with something it
530 finds in DMI or ACPI tables. You can change this
531 at module load time (for a module) with::
532
533 modprobe ipmi_ssif.o
534 addr=<i2caddr1>[,<i2caddr2>[,...]]
535 adapter=<adapter1>[,<adapter2>[...]]
536 dbg=<flags1>,<flags2>...
537 slave_addrs=<addr1>,<addr2>,...
538 tryacpi=[0|1] trydmi=[0|1]
539 [dbg_probe=1]
540 alerts_broken
541
542 The addresses are normal I2C addresses. The adapter is the string
543 name of the adapter, as shown in /sys/bus/i2c/devices/i2c-<n>/name.
544 It is *NOT* i2c-<n> itself. Also, the comparison is done ignoring
545 spaces, so if the name is "This is an I2C chip" you can say
546 adapter_name=ThisisanI2cchip. This is because it's hard to pass in
547 spaces in kernel parameters.
548
549 The debug flags are bit flags for each BMC found, they are:
550 IPMI messages: 1, driver state: 2, timing: 4, I2C probe: 8
551
552 The tryxxx parameters can be used to disable detecting interfaces
553 from various sources.
554
555 Setting dbg_probe to 1 will enable debugging of the probing and
556 detection process for BMCs on the SMBusses.
557
558 The slave_addrs specifies the IPMI address of the local BMC. This is
559 usually 0x20 and the driver defaults to that, but in case it's not, it
560 can be specified when the driver starts up.
561
562 alerts_broken does not enable SMBus alert for SSIF. Otherwise SMBus
563 alert will be enabled on supported hardware.
564
565 Discovering the IPMI compliant BMC on the SMBus can cause devices on
566 the I2C bus to fail. The SMBus driver writes a "Get Device ID" IPMI
567 message as a block write to the I2C bus and waits for a response.
568 This action can be detrimental to some I2C devices. It is highly
569 recommended that the known I2C address be given to the SMBus driver in
570 the smb_addr parameter unless you have DMI or ACPI data to tell the
571 driver what to use.
572
573 When compiled into the kernel, the addresses can be specified on the
574 kernel command line as::
575
576 ipmb_ssif.addr=<i2caddr1>[,<i2caddr2>[...]]
577 ipmi_ssif.adapter=<adapter1>[,<adapter2>[...]]
578 ipmi_ssif.dbg=<flags1>[,<flags2>[...]]
579 ipmi_ssif.dbg_probe=1
580 ipmi_ssif.slave_addrs=<addr1>[,<addr2>[...]]
581 ipmi_ssif.tryacpi=[0|1] ipmi_ssif.trydmi=[0|1]
582
583 These are the same options as on the module command line.
584
585 The I2C driver does not support non-blocking access or polling, so
586 this driver cannod to IPMI panic events, extend the watchdog at panic
587 time, or other panic-related IPMI functions without special kernel
588 patches and driver modifications. You can get those at the openipmi
589 web page.
590
591 The driver supports a hot add and remove of interfaces through the I2C
592 sysfs interface.
593
594 The IPMI IPMB Driver
595 --------------------
596
597 This driver is for supporting a system that sits on an IPMB bus; it
598 allows the interface to look like a normal IPMI interface. Sending
599 system interface addressed messages to it will cause the message to go
600 to the registered BMC on the system (default at IPMI address 0x20).
601
602 It also allows you to directly address other MCs on the bus using the
603 ipmb direct addressing. You can receive commands from other MCs on
604 the bus and they will be handled through the normal received command
605 mechanism described above.
606
607 Parameters are::
608
609 ipmi_ipmb.bmcaddr=<address to use for system interface addresses messages>
610 ipmi_ipmb.retry_time_ms=<Time between retries on IPMB>
611 ipmi_ipmb.max_retries=<Number of times to retry a message>
612
613 Loading the module will not result in the driver automatcially
614 starting unless there is device tree information setting it up. If
615 you want to instantiate one of these by hand, do::
616
617 echo ipmi-ipmb <addr> > /sys/class/i2c-dev/i2c-<n>/device/new_device
618
619 Note that the address you give here is the I2C address, not the IPMI
620 address. So if you want your MC address to be 0x60, you put 0x30
621 here. See the I2C driver info for more details.
622
623 Command bridging to other IPMB busses through this interface does not
624 work. The receive message queue is not implemented, by design. There
625 is only one receive message queue on a BMC, and that is meant for the
626 host drivers, not something on the IPMB bus.
627
628 A BMC may have multiple IPMB busses, which bus your device sits on
629 depends on how the system is wired. You can fetch the channels with
630 "ipmitool channel info <n>" where <n> is the channel, with the
631 channels being 0-7 and try the IPMB channels.
632
633 Other Pieces
634 ------------
635
636 Get the detailed info related with the IPMI device
637 --------------------------------------------------
638
639 Some users need more detailed information about a device, like where
640 the address came from or the raw base device for the IPMI interface.
641 You can use the IPMI smi_watcher to catch the IPMI interfaces as they
642 come or go, and to grab the information, you can use the function
643 ipmi_get_smi_info(), which returns the following structure::
644
645 struct ipmi_smi_info {
646 enum ipmi_addr_src addr_src;
647 struct device *dev;
648 union {
649 struct {
650 void *acpi_handle;
651 } acpi_info;
652 } addr_info;
653 };
654
655 Currently special info for only for SI_ACPI address sources is
656 returned. Others may be added as necessary.
657
658 Note that the dev pointer is included in the above structure, and
659 assuming ipmi_smi_get_info returns success, you must call put_device
660 on the dev pointer.
661
662
663 Watchdog
664 --------
665
666 A watchdog timer is provided that implements the Linux-standard
667 watchdog timer interface. It has three module parameters that can be
668 used to control it::
669
670 modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type>
671 preaction=<preaction type> preop=<preop type> start_now=x
672 nowayout=x ifnum_to_use=n panic_wdt_timeout=<t>
673
674 ifnum_to_use specifies which interface the watchdog timer should use.
675 The default is -1, which means to pick the first one registered.
676
677 The timeout is the number of seconds to the action, and the pretimeout
678 is the amount of seconds before the reset that the pre-timeout panic will
679 occur (if pretimeout is zero, then pretimeout will not be enabled). Note
680 that the pretimeout is the time before the final timeout. So if the
681 timeout is 50 seconds and the pretimeout is 10 seconds, then the pretimeout
682 will occur in 40 second (10 seconds before the timeout). The panic_wdt_timeout
683 is the value of timeout which is set on kernel panic, in order to let actions
684 such as kdump to occur during panic.
685
686 The action may be "reset", "power_cycle", or "power_off", and
687 specifies what to do when the timer times out, and defaults to
688 "reset".
689
690 The preaction may be "pre_smi" for an indication through the SMI
691 interface, "pre_int" for an indication through the SMI with an
692 interrupts, and "pre_nmi" for a NMI on a preaction. This is how
693 the driver is informed of the pretimeout.
694
695 The preop may be set to "preop_none" for no operation on a pretimeout,
696 "preop_panic" to set the preoperation to panic, or "preop_give_data"
697 to provide data to read from the watchdog device when the pretimeout
698 occurs. A "pre_nmi" setting CANNOT be used with "preop_give_data"
699 because you can't do data operations from an NMI.
700
701 When preop is set to "preop_give_data", one byte comes ready to read
702 on the device when the pretimeout occurs. Select and fasync work on
703 the device, as well.
704
705 If start_now is set to 1, the watchdog timer will start running as
706 soon as the driver is loaded.
707
708 If nowayout is set to 1, the watchdog timer will not stop when the
709 watchdog device is closed. The default value of nowayout is true
710 if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not.
711
712 When compiled into the kernel, the kernel command line is available
713 for configuring the watchdog::
714
715 ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t>
716 ipmi_watchdog.action=<action type>
717 ipmi_watchdog.preaction=<preaction type>
718 ipmi_watchdog.preop=<preop type>
719 ipmi_watchdog.start_now=x
720 ipmi_watchdog.nowayout=x
721 ipmi_watchdog.panic_wdt_timeout=<t>
722
723 The options are the same as the module parameter options.
724
725 The watchdog will panic and start a 120 second reset timeout if it
726 gets a pre-action. During a panic or a reboot, the watchdog will
727 start a 120 timer if it is running to make sure the reboot occurs.
728
729 Note that if you use the NMI preaction for the watchdog, you MUST NOT
730 use the nmi watchdog. There is no reasonable way to tell if an NMI
731 comes from the IPMI controller, so it must assume that if it gets an
732 otherwise unhandled NMI, it must be from IPMI and it will panic
733 immediately.
734
735 Once you open the watchdog timer, you must write a 'V' character to the
736 device to close it, or the timer will not stop. This is a new semantic
737 for the driver, but makes it consistent with the rest of the watchdog
738 drivers in Linux.
739
740
741 Panic Timeouts
742 --------------
743
744 The OpenIPMI driver supports the ability to put semi-custom and custom
745 events in the system event log if a panic occurs. if you enable the
746 'Generate a panic event to all BMCs on a panic' option, you will get
747 one event on a panic in a standard IPMI event format. If you enable
748 the 'Generate OEM events containing the panic string' option, you will
749 also get a bunch of OEM events holding the panic string.
750
751
752 The field settings of the events are:
753
754 * Generator ID: 0x21 (kernel)
755 * EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format)
756 * Sensor Type: 0x20 (OS critical stop sensor)
757 * Sensor #: The first byte of the panic string (0 if no panic string)
758 * Event Dir | Event Type: 0x6f (Assertion, sensor-specific event info)
759 * Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3)
760 * Event data 2: second byte of panic string
761 * Event data 3: third byte of panic string
762
763 See the IPMI spec for the details of the event layout. This event is
764 always sent to the local management controller. It will handle routing
765 the message to the right place
766
767 Other OEM events have the following format:
768
769 * Record ID (bytes 0-1): Set by the SEL.
770 * Record type (byte 2): 0xf0 (OEM non-timestamped)
771 * byte 3: The slave address of the card saving the panic
772 * byte 4: A sequence number (starting at zero)
773 The rest of the bytes (11 bytes) are the panic string. If the panic string
774 is longer than 11 bytes, multiple messages will be sent with increasing
775 sequence numbers.
776
777 Because you cannot send OEM events using the standard interface, this
778 function will attempt to find an SEL and add the events there. It
779 will first query the capabilities of the local management controller.
780 If it has an SEL, then they will be stored in the SEL of the local
781 management controller. If not, and the local management controller is
782 an event generator, the event receiver from the local management
783 controller will be queried and the events sent to the SEL on that
784 device. Otherwise, the events go nowhere since there is nowhere to
785 send them.
786
787
788 Poweroff
789 --------
790
791 If the poweroff capability is selected, the IPMI driver will install
792 a shutdown function into the standard poweroff function pointer. This
793 is in the ipmi_poweroff module. When the system requests a powerdown,
794 it will send the proper IPMI commands to do this. This is supported on
795 several platforms.
796
797 There is a module parameter named "poweroff_powercycle" that may
798 either be zero (do a power down) or non-zero (do a power cycle, power
799 the system off, then power it on in a few seconds). Setting
800 ipmi_poweroff.poweroff_control=x will do the same thing on the kernel
801 command line. The parameter is also available via the proc filesystem
802 in /proc/sys/dev/ipmi/poweroff_powercycle. Note that if the system
803 does not support power cycling, it will always do the power off.
804
805 The "ifnum_to_use" parameter specifies which interface the poweroff
806 code should use. The default is -1, which means to pick the first one
807 registered.
808
809 Note that if you have ACPI enabled, the system will prefer using ACPI to
810 power off.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.